In a medium saucepan of boiling water, blanch the shallots for 3 minutes; drain. Return the shallots to the pan, add the oil, coriander seeds, peppercorns, garlic, lemon zest and juice, celery, bay leaf, thyme, parsley and sugar and simmer over moderately low heat, stirring a few times, until the shallots are very tender, about 30 minutes. Fold in the scallion and season with salt.
The confit can be refrigerated for up to 2 days. Reheat gently.
Steaks, tuna steaks, pork or veal chops, country terrines, bluefish, mackerel, cold roast pork.